Carburetor



Sept 14, 1937- v J. E. MULLEN, JR 2,093,205

CARBURETOR Filed Deo. 5, 1934 5 Sheets-Sheet 1 QD QB Sept. 14, 1937. J.FJMULLEN, JR

CARBURETOR 3 Sheets-Sheet 2 Filed Dec. 5, 1934 Sept. 14, 1937.

Filed Dec. 5, 1934 J. F. MULLENl JR cARBUREToR y 3 Sheets-Sheet 3 lglgPatented Sept. 14, 1937 UNITED STATES PATENT OFFICE 19 Claims.

This invention relates to carburetors, such as those employed oninternal combustion engines, and more particularly to those in which thegasoline or other liquid fuel is automatically fed into the incomingstream of air by gravity, as well as by suction.

Generally stated, the object of the invention is to provide a novel andimproved construction and arrangement whereby the combined gravity andsuction feed is more efficiently employed in a carburetor of thisgeneral character, thereby to increase the-eiliclency of the engine ormotor, and to increase the mileage per gallon of. fuel.

It is also an object to provide certain details and features ofconstruction and combinations tending to increase the general eiiiciencyand the desirability of a carburetor of this particular character.

To the foregoing and other useful ends, the invention consists inmatters hereinafter set forth and claimed and shovm in the accompanyingdrawings, in which- Fig. 1 is a plan view of the carburetor embodyingthe principles of the invention.

Fig. 2 is a section on line 2 2 in Fig. 1 of the drawings.

Fig. 3 is a detail or fragmentary section on line 3 3 in Fig. 1 of thedrawings.

Fig. 4 is a plan view showing a double-barrelled carburetor, instead ofthe single-barrelled carburetor previously described.

Fig. 5 is a vertical section on line 5 5 in Fig. 4 of the drawings.

Fig. 6 is a horizontal section on line 6 6 in Fig. 5 of the drawings.

Fig. l is a vertical section o`n line 'I 'I in Fig. 4 of the drawings.

Fig. 8 is a vertical section on line 8 8 in Fig. 4 of the drawings.

Fig. 9 is a fragmentary detail sectional view showing a different formof the invention.

Fig. 10 is a similar view showing another form of the invention.

Fig. 11 is a view similar to Fig. 2, showing a different form of theinvention.

As thus illustrated, referring to Figs. 1, 2 and 3 of the drawings, thecarburetor has a float chamber I provided with a float 2 of ordinaryform, which maintains the level of the fuel at line 3, normally, in themanner shown in Fig. 2 of the drawings. 'I'he body 4 of the carburetorhas an upper air intake chamber 5, provided with the ordinary chokevalve 6, and this chamber is connected by the Venturi tube passage 'Iwith the lower chamber 8, containing the ordinary throttle valve 9, asshown. This is what is called a down draft carburetor, and the bottomportion I0 is bolted to the intake manifold of the engine or motor.

It will be seen that the walls of the float chamv5 ber I are providedwith a passage II that connects at one end to the fuel inlet nozzle I 2,in the Venturi tube passage 1, and that connects at its upper end to thevertical passages I3 and I4, the latter having its inlet end slightlybelow 10 the level of the fuel, and the passage I3 having its lowerinlet end I5 near the bottom of the float chamber. An auxiliary fuelnozzle I6 is also disposed in the Venturi tube passage, as shown, and isconnected by passages I'I, I8 and I9 with 15 the outlet 20 near thebottom of the float chamber. It will also be seen that the oat chamber lhas an air inlet passage 2I to maintain the required atmosphericpressure in the upper portion of the ioat chamber.

-20 In the other side of the carburetor body, there is a verticallydisposed cylindrical chamber 22 in which the valve body 23 is movable upand,l

down, this valve body having an upper coneshaped valve 24for engagementwith the tapered 25 valve vseat 25 at the top of the said chamber.

This valve seat 25 is connected by a passage 26 with the passages II andI8, as shown in dotted lines in Fig. 2 of the drawings. A coil spring21, applied as shown, serves to hold the valve 24 in 30 normally raisedor closed position. The lower end of the chamber 22 is connected by apassage 28 with the throttle valve passage 8, at a point below the valve9, as shown in the drawings. An air vent 29 connects the upper portionof the 35 chamber 22, above the valve body 23, to the chamber 5 wherethe air enters the carburetor.

As shown in Fig. 3, the float 3 operates the ordinary or suitable inletvalve 30 to automatically admit fuel to the oat chamber, and to shut o.40 the fuel at the right time, thereby to normally maintain the fuellevel at the line 3, as shown in Fig. 2 of the drawings.

'I'he height of the fuel level 3 above the jet or nozzle I2 provideswhat is known as a positive 45 static head. I

Before the engine is started, the liquid fuel level is approximately atthe line 3I, which is a slight distance below the inlet opening 32 ofthe passage I4, and the valve 24 is tightly against its seat 25, 50 sothat no air can enter the passage 26 and the passage I1, but when themotor is started, then the liquid fuel from the pump, such as theordinary feed pump on a motor vehicle, brings the level of the fuel inthe float chamber a slight 55 2 distance above the opening 22, in thepassages I2 and I4, and thereby seals these passages, in order that noair may gain an entrance through the opening 22, in a manner that willbe readily understood. The suction caused by the pistons of the motorcauses air to flow into the carburetor at the inlet passage 9, throughthe Venturi passage 1, past the throttle 9, and then to the intakemanifold of the motor. This suction, operating through passage 29,causes the valve 24 to move downwardly away from its seat 25, and causesa suction action at the outlets of the jets and nozzles I2 and I6, andthe suction causes the fuel to flow through passage II to jet I2 whereit mixes with the air flowing through the carburetor. The suction whichacts on jet I9 tends to cause the liquid fuel to flow through passagesI1, I2 and I9, but this is prevented, for the reason that air is free toenter through the passage 29, and consequently the suction is notsuiflcient to raise the fuel in passage I2 high enough to overflowthrough the passage I9 into the passage I1. When, however, the throttle9 is suddenly opened,

or the suction of the intake manifold is decreased sufficiently, thespring 21 forces the valve 24 upwardly against its seat 29 and therebycloses the air passage 29, so that the suction is then effective toraise the fuel in passage I9 and cause it to overflow through thepassage I 9 into the passage I1, and to cause it to discharge from theJet I6 into the air flowing through the carburetor. In this way, theacceleration is automatic. so to speak, and the fuel is fed into the airstream by gravity, as well as by suction, for the passages I I and I1,it will be seen, are really parts of two siphons that would permit thefeeding of the fuel by gravity until the level of t he fuel reaches theoutlet openings I9 and 20 near the bottom of the oat chamber; but. ofcourse, as shown in Fig. 2, the passage I1 cannot function as a gravitysiphon if the passage 2l is open, and, of course, for the siphon passageII to drain the fuel in the carburetor down to the level of the openingIl would require that the opening 22 be closed: but, in effect, asstated, the passages II and I1, in combination with the passages I2 andI9, constitute siphons that operate by gravity to feed the fuel into theincoming current of air, and that also operate by suction.

And, in addition, it will be understood that in Fig. 2 of the drawingsthe valve 24 is shown nearly closed, inasmuch as at this time. with thethrottle 9 in the position shown, or even in a somewhat more closedposition, there is some suction exerted in the passage 2l, sufiicient tomaintain the valve 24 slightly open, so that the lsiphon passage I1 willnot function to feed fuel to the mixing chamber; but, when the engine isaccelerated, by completely opening the throttle 9, suction on thepassage 22, by the engine, will practically cease, and the valve 24 willclose, thereby shutting oil' the emission of air to the passage 22, andvat such time the passages I1 and I2 and I9 will operate to feed fuelinto the mixing chamber.

'I 'he carburetor shown and described is, in general principle, what isordinarily called a down draft carburetor. However, it is obvious thatthe invention can be employed in an up draft or a side draft carburetor,equally well, inasmuch as the combination suction and gravity feed, withthe positive `static head principle, is adapted to work or function onall of these different types of curburetor.

Obviously, when the motor stops, there will be a little discharge offuel into the passages 1 and 2, from the jet I2, and perhaps from theJet Il, but'this will simply serveto prime the engine when it is againstarted. In Figs. 4, 5, 6, 7 and 8, the construction is substantiallythe same as that previously described, but in this case the device iswhat is called a double-barrelled carburetor, instead of beingsingle-barrelled like the one previously described. In this case,therefore, the carburetor has two downwardly extending mixing passages22 and 22, arranged side by side, and with the fuel jets 24 and. 25extending into the restricted or Venturi portions of these passages.these Jets being connected .to the float chamber 26 in the mannerpreviously described, and the arrangement being substantially the same,except that the carburetor is double, so to speak, having twice as manyfuel Jets and having a throttle valve 2l for the lower end of eachpassage 22, to throttle or vregulate the mixture passing from thecarburetor into the intake manifold of the motor.

Referring to Fig. 9, the construction is similar to that shown in Fig. 2o'f the drawings, but in this case the action is somewhat different,inasmuch as the float chamber has no siphon inlet 22, and has insteadmerely the one inlet 29, and a small air hole 29 communicating with thetop or bend of the siphon.

In Fig. 10, the construction is similar to that shown in Fig. 2 of thedrawings, except in this case there is no full opening 22, but insteadthere is a very small restricted opening 29 at the lower end of theupper ieg of the siphon.

Referring to Fig. 11, it will be seen that the construction here issimilar to that previously described, but in this case the mixingchamber 42 is straight and has no Venturi portion where the jets 4I and42 are located therein. Also, in this form of the invention, the floatchamber has no siphon inlet 22, but has only the lower siphon opening42, so that the jet 4I is only connected through the opening 42 with thefuel chamber. However, the top of the siphon has a passage 44 leading tothe air chamber 49, into which air enters through the passage 49, whenthe valve 41 is in raised or normal position. 'Ihe upper end of thevalve stem 49 has a plunger head 49 that fits the chamber 59 in whichthe coil spring 5I is located, which spring keeps the valve and theplunger in normally raised position. The top of the chamber 99, abovethe plunger 49, is provided with an air vent 92,- as shown. A passage I2extends from an opening 94 in the side oi the passage 40, below thethrottle 59, to an opening 56 at the bottom of the chamber 59, whereby,under the suction of the engine, exerted through the passage 52, theplunger 49 will be sucked downwardly, causing the valve 41 to close thepassages 44 and 49, thereby shutting off the entrance of any air intothe siphon passage which leads to the jet 4I previously mentioned.

In each form of the invention, therefore, except in Fig. 1l, it will beseen that the fuel has two levels in the float chamber, the normal levelbeing. somewhat lower than the level at which the fuel is maintainedduring the-running of the engine or motor, as in each case some fueldrains out of the siphon passages when the motor stops, thus loweringthe level of the fuel in the float cham-- ber. Also, therefore, in eachform of the invention, there is a positive static head thatcharacterizes the combined suction and gravity feed of the fuel. This,it is found, in actual practice, insures greater efficiency for theengine or motor,`

and better mileage per gallon in the consumption of the fuel.

With further reference to Fig. 9, it will be understood that the airinlet Il is preferably so small that the passage of air therethroughwill not break the siphon action while the engine is running; but, `whenthe engine stops running, then the opening Il is sufllcient to admitenough air to break the siphon action, preventing the siphon passagesfrom draining the fuel down to the level of the opening 38, as will bereadily understood.

Furthermore, in connection with Fig. l of the drawings, it will beunderstood that the opening 39 is also so small that, should theautomobile lurch to one side, and thereby cause the level of the fuel tomomentarily go below this opening, the intake of air will not besufficient to break the siphon action at such time; but, of course, whenthe engine stops running, and the level of the fuel then goes below thelevel of the opening 39, the

latter is then operative to admit enough air tov break the siphon actionand stop the draining of the fuel into the mixing passage or chamber ofthe carburetor.

It will be seen, therefore, that in each ferm of the invention there aremeans forming in effect a siphon between the float chamber and the airpassage, adapted to feed the fuel by suction of gravity into the airstream, forming the main fuel passage from the float chamber to themixing chamber, all of the elements being co-ordinated to maintain thelevel of the fuel in the float chamber at a point high enough above thelower outlet `end of the siphon to maintain a positive static head,while the motor is in operation, and that this is true of each of thedifferent forms of the invention shown and described.

In each form of the invention, it will be seen. 40 both gravity and thesuction of a Venturi tube are employed, along with a main fuel passagethat is normally open and free from direct manual control, for the mainfuel passage in each form of the invention is without any manual 45throttle control, and is normally open, and this also holds good for thepower range, in each form of the invention. For acceleration, in eachform of the invention, there is a vacuum operated valve, to increase theflow of fuel, but without 50 restricting the intake of air. lAlso, theflow at idling, in each form of the invention, is almost entirely bygravity because of the low velocity of air through the main barrel ofthe carburetor. Then, as the ow of air increases, the suction of 55 theventuri becomes stronger, and the gravity feed alone gets weaker,relatively, as the air flow increases, whereas the suction feed getsstronger, thus insuring more approximately the ideal combination ofgravity and suction feed.

Thus, with the construction shown in Fig.- 2 of the drawings, when thethrottle 9 is opened sufficiently to cause an appreciable drop in theintake manifold vacuum, the valve 23 automatically seats itself, thuscutting off the air supply to the 65 nozzle I6, which causes fuel todischarge from the nozzle I6, thus giving the needed increase in mixturestrength for acceleration, or for carrying an increased load at aboutthe same speed.

, Of course, the throttle 9 need not be opened wide- 70 to cause theappreciable drop in the intake manifold vacuum. In Fig. 1l of thedrawings, the Vvalve 41 remains closed as long as the engine is running,or is being turned over by the starting motor or by hand, for as long asthe engine is 75 being turned over there is always more or less vacuumat I4, which serves to keep thevaive l1 closed. Preferably, the springII under the valve l1 is of such strength or tension that the valve 41opens when an appreciable drop in the intake manifold vacuum occurs, andunder such conditions fuel stops discharging from the nozzle- II and theengine runs on the discharge from nozzle 42 only. Therefore, the spring21 under the valve 23 is preferably slightly stronger than the spring Iunder the valve 41, in order that fuel may flow out of the auxiliarysiphon before the ilow in the main siphon is stopped, and will continuefor a short time after the valve 41 is closed, to give the main passagetime to start. This overlapping of flow, as between the two siphons,tends to prevent any stoppage of the flow of fuel to the engine ormotor. Therefore, air is admitted to the main siphon, in Fig. 11, tostop the flow of fuel, so that the float bowl will not be drained ywhenthe engine stops. Similarly, air is` admitted to the auxiliary siphon toprevent acceleration, when acceleration is not wanted, and to preventthe draining of the float bowl when, in starting the engine, the motorfails to respond promptly. The spring under the valve 2l may besufficiently strong to hold this valve in seated position while theengine is being turned over by the starter or by hand. This causes fuelto flow out of the nozzle I6, as well as out of the nozzle I2, and then,if the motor fails to respond, and the starting is momentarilyabandoned, the air inlet to the auxiliary siphon prevents draining ofthe float bowl.

It will be seen that, in each form of the invention, the passage 26forms the sole air admission to the auxiliary fuel feed pe formed by thepassages I1, I8, and Il, as there is no other way in which air can enterthis siphon passage, and hence the suction opening at the lower end ofthe passage 28 has entire control over the admission of air to theauxiliary fuel feed passage.

In each form of the invention, therefore, the main siphon fuel passagehas means for admitting air thereto, in one way or another, to preventdrainage of the iloat chamber. In Fig. 2 air is admitted at 32, when thelevel of the fuel is lowered, while in Fig. 9, air is admitted at 39,sufficiently to insure the desired result, and in Fig. 10 air isadmitted at 39 to prevent drainage; and in Fig. l1, as explained, airisadmitted to the main fuel passage at 44, in the manner explained;whereby, in each form of the invention, the main fuel passage isincapable of draining the iloat chamber, as for example when the enginestops running.

What I claim as my invention is:

1. In a throttle controlled carburetor for a motor, means providing ageneral air passage through which the air ows to the motor, providing amixing chamber, means providing a float chamber for the liquid fuel, andmeans forming in effect a siphon between the float chamber and the airpassage, with a fixed inlet and fixed outlet, adapted to feed the fuelby suction and gravity into the air stream, forming the main fuelpassage from the float chamber to the mixing chamber, normally open,free at all times from any direct manual regulation or valve control,with means to admit air to said passage to prevent draining of the floatchamber, all co-ordinated to maintain the level of the fuel in the floatchamber at a point high enough above the outlet end of the siphon tomaintain a positive static head, while the motor is running, to providethe same gravity and suction feed for both the power range and theeconomy range.

2. A structure as specified in` claim 1, comprising an auxiliary siphonpassage for feeding fuel from the float chamber to the air passage, bysuction and gravity, together with an automatic 5 valve and an airpassage controlled thereby to the auxiliary siphon. for automaticallyfeeding additional fuel to the air stream for acceleration.

3,. A structure as specified in claim l, said siphon having two inletsin the float chamber, one inlet a substantial distance below the other.

4. A structure as specified in claim l, said siphon having two inletopenings in said float chamber, one above the other, the upper openingbeing below the said level of the fuel when the engine is running, butabove the level of the fuel when the engine is not in operation, and theother opening being near the bottom of the float chamber.

5. A structure as specified in claim 1, comprising auxiliary means forautomatically feeding fuel from the float chamber to the air stream, bysuction and gravity, for acceleration, and valve means controlling theair stream and thereby indirectly controlling the feeding of fuel tosaid stream.

6. In a carburetor for a motor, means providing a general air passagethrough which the air flows to the motor, means providing a floatchamber for the liquid fuel, means forming in effect a siphon passagebetween the float chamber and the ali` passage, adapted to feed thefuelby suction and gravity into the air stream, cooperating with the floatand the inlet controlled by the latter to maintain the level of the fuelin the float chamber at a point high enough above the lower outlet endof the siphon to maintain a 1 positive static head, while the motor isrunning,

said siphon having two inlets in the float chamber, one inlet asubstantial distance below the 40 other.

7. In a carburetor for a motor, means providing a general air passagethrough which the air flows to the motor, means providing a floatchamber for the liquid fuel, means forming in 45 effect a siphon passagebetween the float chamber and the air passage, adapted to feed the fuelby suction and gravity into the air stream, cooperating with the floatand the inlet controlled by the latter to maintain the level of the fuelin 50 the iloat chamber at a point high enough above the lower outletend of the siphon to maintain a positive static head, while the motor isrunning,

said siphon having two inlet openings in said float. chamber, one abovethe other, the upper 55 opening being below the said level of the fuelwhen the engine is running, but above the level of the fuel when theengine is not in operation, and the other opening being near the bottomof the float chamber.

8. In a carburetor for a motor, means providing a general air streampassage through which the air flows to the motor, means providing afloat chamber for the liquid fuel, means forming in effect a siphonpassage between the float G5 chamber and the air passage, adapted tofeed the fuel by suction and gravity into the air stream, co-operatingwith the oat and the inlet controlled by the latter to maintain thelevel of the fuel in the float chamber at a point high 10 enough abovethe lower outlet end of the siphon to maintain a positive static. head.while the motor is running, van auxiliary siphon passage between thefloat chamber and the air stream passage, for feeding fuel from thefloat chamber to 75 the air passage, by suction and gravity, togetherwith means including an automatic valve and an air passage controlledthereby, for automatically feeding additional fuel through the auxiliarysiphon passage to the air stream for acceleration.

9. In a carburetor for a motor, having an air inlet control, suction andgravity siphon feed means providing' a main feed passage for feeding thefuel in the same way for both the economy range and the power range, andseparato auxiliary suction and gravity siphon feed means to lincreasethe flow of fuel for acceleration, operable independently of said airinlet control.

10. A structure as specified in claim 9, said siphon means having aplurality of fluid inlets.

1l. A structure as specified in claim 9, said auxiliary means comprisinga siphon fuel feed passage having a plurality of fluid inlets one ofwhich is an air inlet controlled by a suction operated valve. y

12. A structure as specified in claim 9, said siphon means having an airinlet.

13,'A structure as specified in claim 9, said auxiliary means having anair inlet.

14. A structure as specified in claim 9, said siphon means having aplurality of fuel inlets.

15. A structure as specified in claim 9, said main uell passage beingfree from direct manual con- 16. In a carburetor for a motor, a throttlevalve, means forming a siphon fuel feed'passage, for feeding the fuel bysuction and gravity to the interior of the carburetor, in the same wayfor both the power and the economy range, and valve means controlled bya suction passage leading to an opening between the throttle valve andthe motor for at certain times preventing feeding of the fuel byadmitting air to the top of the siphon. forming the sole air admissionto said fuel passage, said siphon forming anauxiliary acceleration fuelfeed passage, and another siphon forming the main fuel feed passage.

17. A structure as specified in claim 1, in which the carburetor is ofthe double-barrelled type, having two air passages with the said siphonfuel feed passage arrangement for each barrel or air passage, and withthe said single float chamber common to both barrels of the carburetor.

18. In a carburetor for a motor, means providing a general air passagethrough which the air flows to the motor, means providing a floatchamber for the liquid fuel, means forming in effect a siphon passagebetween the 'float chamber and the air passage, forming the main fuelpassage to the mixing passage, normally open, free at all times from anydirect manual regulav tion or valve control, adapted to feed the fuel bysuction and gravity into the air stream, cooperating ,with the float andthe inlet controlled by the latter to maintain the level of the fuelmotor, means providing a general air passage 'through which the airflows to the motor, means the main fuel passage to the mixing pesage,normally open, free at all times from any direct manual valve control,adapted to feed the fuel by suction and gravity into the air stream,cooperating with the iioat and the inlet controlled by the latter tomaintain a positive static head, while the motor is running, the saidcarburetor being of the double-barrelled type, having two air passageswith the said siphon fuel passage arrangement for each barrel or airpassage, and with the said single iioat chamber common to both barrelsof the carburetor, a throttle for each barrel, and air admission controlmeans having a suctioncontrol opening between each throttle and theengine.

JAMES F. MULLEN, JR;

